How do substances pass through cell membranes? 2.0 / 5 based on 1 rating ? BiologyCellular processes and structureASEdexcel Created by: Hashim HuseinCreated on: 08-01-13 11:45 How do substances pass through cell membranes? Diffusion: from a high to low concentration until equilibrium reached carries hydrophobic (lipid-soluble) or small uncharged molecules through phospholipid bilayer passive, no energy is required Facilitated diffusion: from a high to low concentration until equilibrium reached hydrophilic molecules or ions through channel proteins or via carrier proteins that change shape passive, no energy required Active transport against a concentration gradient, from low to high through a carrier protein that changes shape requires energy, ATP 1 of 2 How do substances pass through cell membranes? Osmosis: a type of diffusion involving movement of free water molecules high to low concentration of free water molecules until equilibrium is reached through phospholipid bilayer passive, no energy required Exocytosis: used for bulk transport of substances out of the cell vesicles fuse with the cell surface membrane, releasing their contents Endocytosis: used for bulk transport into the cell vesicles are created from the cell surface membrane, bringing their contents into the cell 2 of 2
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